JPS581016Y2 - 3 color separation imaging device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a three-color separation imaging device, and in an optical system that separates input light into three colors using a dichroic mirror, a trimming filter with high transmittance is used only for the green channel, and the overall sensitivity is high. Another object of the present invention is to provide an imaging device with excellent color reproducibility, especially in the green channel.

Generally, as shown in Figure 1, in order to obtain ideal characteristics, a trimming filter is used that has the characteristic of only passing light with a central wavelength of red for the red channel, green for the green channel, and blue for the blue channel. Ta.

However, filters having such characteristics each have a low transmittance at each center wavelength, and the low transmittance for the green channel in particular has the drawback of reducing the sensitivity of the entire camera.

The present invention eliminates the above-mentioned drawbacks, and an embodiment thereof will be described with reference to FIG. 2 and subsequent figures.

FIG. 2 shows an embodiment of the three-color separation imaging device according to the present invention.

1 is a first relay lens, and light from the subject passes through this first relay lens.

The blue light, which is the short wavelength component of that light, is shown in Figure 3a.
Blue reflective dichroic mirror 2 with reflective characteristics shown in
reflected.

This reflected and extracted blue channel light is reflected by the mirror 3.
After passing through the second relay lens 4, it enters the blue channel image pickup tube 10.

On the other hand, among the remaining green and red light components that have passed through the mirror 2, the red light component is reflected by the red reflective dichroic mirror 5 having the reflection characteristics shown in FIG. 3C.

The reflected and extracted red light component is totally reflected by the mirror 6, passes through the second relay lens 7, and then enters the red channel image pickup tube 11.

Furthermore, the remaining green component with the characteristic indicated by b in FIG. 3 passes through a red reflective dichroic mirror 5, passes through a short wavelength cut yellow filter (trimming filter) 8, and passes through a second relay lens into the trailing edge channel image pickup tube. incident on .

As shown in FIG. 4, the trimming filter 8 has a transmission characteristic that has a central wavelength of yellow and cuts only wavelengths shorter than this.

As a result, the third ink that has passed through the dichroic ink mirrors 2 and 5 is
The green component with the characteristic indicated by b in the figure is the trimming filter 8.
When passing through, the short wavelength side is slightly cut off, resulting in the characteristic shown by b' in FIG.

When considering the color reproducibility of the green channel, a delicate problem with the ideal characteristics of the green channel is the point of separation from the blue channel.

That is, the ideal imaging spectral sensitivity curve when considering only the positive polarity signal of the NTSC system is as shown in Figure 6, and R, G,
B shows the characteristic curves of the red, green and blue channels, respectively.

At N, the intersection of curves B and G is P. The intersection point of music 1fiG and R is Q, and the position of point P among them is the problem as described above.

Therefore, as mentioned above, each channel light that has just passed through each dichroic □ler has the characteristics as shown in Fig. 3, and the position of the intersection Q' of the green channel light and the red channel light C is the point in Fig. 6. Although the position of the point P where the green channel light intersects with the blue channel light a is very different from the position of point P in FIG.

However, the characteristics of the green channel light after passing through the filter 8 are as shown in b' in FIG. is approximated to point P.

Therefore, good color reproducibility can be obtained for the green channel.

Moreover, since the trimming filter 8 has a characteristic of trimming only the short wavelength side, the transmittance is high, and therefore the sensitivity hardly decreases.

Furthermore, since no trimming filter is used for the other channel lights, the overall sensitivity of the camera is extremely high.

As mentioned above, the three-color separation imaging device devised is such that the red channel light and the blue channel light are separated by a dichroic mirror and then incident on each channel imaging region without using a trimming filter, and only the green channel light is separated from the yellow one. Since it is configured so that it enters the image pickup tube after passing through a trimming filter with high transmittance that cuts only the short wavelength side, there is no decrease in sensitivity for each channel light, and in particular, the effect of low sensitivity of the entire camera is avoided. The overall sensitivity of the camera is higher because the sensitivity decrease is smaller than that of the green channel.Furthermore, the separation point with the blue channel, which affects the color reproducibility of the green channel, is close to the ideal separation point, so especially for the green channel. It has features such as being able to obtain good color reproducibility.

[Brief explanation of drawings]

Fig. 1 is a transmittance characteristic diagram of conventional red, green, and blue trimming filters, Fig. 2 is an optical block system diagram of one embodiment of the imaging device of the present invention, and Fig. 3 is after reflection and passing through each dichroic mirror. Figure 4 is a diagram of the relative sensitivity characteristics of each channel of light, Figure 4 is a diagram of the transmittance characteristics of the trimming filter used in the device of the present invention, Figure 5 is a diagram of the relative sensitivity characteristics of incident light of each channel to each channel for storage, and Figure 6 is It is an ideal imaging spectral sensitivity characteristic diagram. 1... 1st relay lens, 2... Blue reflective mirror, 4, 7, 9... 2nd
Relay lens, 5... Red reflective dichroic mirror, 8... Trimming filter, 10, 11
．． 12... Image tube.

Claims (1)

[Scope of utility model registration request] A three-color separation imaging device configured to separate blue channel light, red channel light, and green channel light from incident light using a blue reflective dichroic mirror and a red reflective dichroic mirror, and trim the separated channel light using a trimming filter. A blue-reflecting dichroic mirror separates blue channel light from the input light and directs it directly into the blue-channel image pickup tube, and a red-reflecting dichroic mirror separates the red channel light from the light that has passed through the blue-reflecting dichroic mirror. The configuration is such that only the remaining green channel light that has passed through the blue and red reflective dichroic mirrors is trimmed using a trimming filter, and then made to enter the green channel imaging tube. Then,
The green trimming filter maintains the red reflective dichroic mirror characteristics of the long wavelength side of the green channel light, while cutting only the wavelength side shorter than the yellow wavelength to correct the intersection of the green channel characteristics and the blue channel characteristics. A three-color separation imaging device characterized in that: